1. Field of the Invention
The present invention relates to a lens barrel and an optical apparatus.
2. Description of the Related Art
Japanese Patent No. 3,328,036 discloses a mirror frame moving unit that is provided at least one of a lens holding frame and an opposite surface of another frame, and includes a reference guide parallel to an optical axis, and a forcing unit configured to apply a force so as to bring both frames into contact via the reference guide. Thereby, Japanese Patent No. 3,328,036 applies a side pressure to the lens holding frame in the zoom lens barrel, prevents optical-axis fluctuations, stabilizes an image, and restrains blurs in a screen. In addition, the forcing unit positions the cam ring in the optical axis direction, and thus miniaturizes the barrel.
However, Japanese Patent No. 3,328,036 has a problem in that due to a sliding load in moving a comparatively heavy lens holding frame, the sliding sounds (noises) occur in the zooming time and in the motion image photography. One conceivable solution for this problem is a method of mounting an image pickup element onto the movable holding frame, but this method requires a driving member and a guide member used to move back and forth each movable holding frame in the optical axis direction, causing the lens barrel to be larger.